Self-adjusting spring set brake



Jan. 5, 1965 LEWYCKYJ 3,164,226

SELF-ADJUSTING SPRING SET BRAKE Filed March 8, 1963 2 Sheets-Sheet lJan. 5, 1965 Filed March 8, 1963 R. LEWYCKYJ SELF-ADJUSTING SPRING SETBRAKE 2 Sheets-Sheet 2 INVENTOR. PUMA/V AEWYCAY/ 3,164,226SELF-ADJUSTING SPRING SET BKE Roman Lewyekyj, Phiiadelphia, Fa.,assignor to I-T-E Circuit Breaker (Iornpany, Philadelphia, Pa, acorporation of Pennsylvania Filed Mar. 8, 1963, Ser. No. 263,907 Claims.(Cl. 188171) This invention relates to a spring set type brake and morespecifically relates to a novel self-adjusting spring set brake whereinthe stop limits for the motion of the operating arm and solenoid magnetbody are automatically readjusted when the air gap between the brakelining and the brake drum varies from some predetermined value.

Accordingly, a primary object of this invention is to provide a novelself-adjusting spring set brake.

Another object of this invention is to provide a novel self-adjustingstructure which can be utilized in combination with commerciallyavailable spring set brakes.

A further object of this invention is to provide a novel stop positionadjustment means for automatically and continuously adjusting the airgap between the brake lining of a brake shoe and a brake drum.

A still further object of this invention is to provide a novelself-adjusting brake wherein the length of a slot which carries a cammeans determines the maximum air gap between the brake lining and drum.

These and other objects of this invention will become apparent from thefollowing description when taken in connection with the drawings inwhich:

FIGURE 1 shows a plan view of a typical prior art type of spring setbrake.

FIGURE 2 is an exploded perspective view of one of the adjustment camsof FIGURE 2 and particularly illustrates the spring connection betweenthe cam and its mounting pin.

FIGURE 3 shows a side plan view of the brake of FIGURE 1 when modifiedaccording to the present invention.

Referring first to FIGURE 1, the brake illustrated therein is a brake ofthe spring set, electrically released, shoe type. Brakes of this typeare typically employed in crane hoists, steel mills, and have utility inmany marine applications.

The brake linin of any type of brake is subject to wear. In electricallyreleased brakes the wear of the brake lining will increase the air gapbetween the armature and its magnet so that the brake must periodicallybe adjusted. In the event that such periodic adjustment is not made, theair gap between the armature and magnet may become too large for theampere turns available in the magnet to operate the brake.

Referring to FIGURE 1, I have illustrated'therein a typical prior artbrake which is contained within housing 10, and is used to control therotation of a brake drum 11 which rotates on a shaft 12. The brake isgenerally comprised of the brake shoe 13, having a lining 14, the brakeshoe 13 being carried on an operating arm 15. The operating arm 15 ispivotally mounted on a fixed pin 15 which is carried in an extension 17of a solenoid containing structure 18. The solenoid containing structure18 is provided with terminals 19 and 21) which are connected to a sourceof D.-C. power in the usual manner. The solenoid winding within housing18 cooperates with an armature 21 through an air gap 22.

Armature 21, brake shoe 13 and operating arm 15 are all connected by acommon pin 23 as illustrated. The upper end of operating arm 15 thenreceives a tongue 24 secured to spring cap 25 which is carried at theend of rod 26. A second spring cap 27 is carried immediately adjacentone side of extension 28 of solenoid body 18 1 United States PatentOfihce 3,1h422t Patentecl Jan. 5., 1965 with rod 26 extending through anopening in extensim 28 and terminating in a threaded end 29 whichreceives bolt 3%). A spring 31 is then captured between caps 21 and 27and exerts a force on operating arm 15 to nor mally bias arm 15counterclockwise about its pivot 11 and thus biases brake shoe lining 14into engagemen with drum 11.

It will be observed that after some period of operation brake lining 14will wear so that the arm 15 will come tr rest at a farther and farthercounterclockwise position Thus the air gap 22 becomes larger after someperiod 0 operation. In order to decrease or adjust this air gap th:solenoid body 18 is provided with a tongue 35 whicl carries an adjustingscrew 36 which seats upon a seating block 37 and is locked into positionby lock nut 38. Thi: arrangement, along with fixed pivot pin 16, whichcar be securely seated in the opposing housing walls of bone ing 1i),serves to fix the position of solenoid body 18.

Assuming now that air gap 22 has increased beyonc some predetermineddesired value, it is necessary it loosen nut 33 so that screw 36 can bethreaded down wardly in tongue 35 to cause the body 18 to move counterclockwise and thus close air gap 22. The structure i: then locked inthis position by locking the lock nut 38 In operation, the brake isnormally set or engaged b3 spring 31. When it is now desired to releasethebrake it is only necessary to energize terminals 19 and 20 trenergize the solenoid within solenoid housing 18 to there by movearmature 21 to the right, closing gap 22 moving the brake shoe 13 to theright and out of engagement witl drum 11. Note that if too much wearoccurs in brak: lining 1 4 the gap 22 can increase to such a value thati would be impossible for solenoid 18 to exert sufficien force onarmature 21 to move the armature to a dis engaged position. For thisreason, it is necessary t( periodically adjust the adjusting screw 36 tomaintaii some given small air gap.

The principle of the present invention is to provide 2 novel brakearrangement which is automatically self-ad justing. The inventiveconcept is illustrated in FIGURL 2 wherein automatically adjusted stoppositions are pro vided for the operating arm 15 and solenoid body 18. Iwill be noted that those components similar to those 0. FIGURE 1 havebeen given similar identifying numeral: in FIGURES 2 and 3.

Referring now to FIGURES 2 and 3, the side wall: and 51 (FIGURE 3) areprovided with slots 52 am 53 respectively which receive a shaft 54therein. The shaft 54- may have enlarged end portions 55 and 56respectively to capture the shaft in the housing. As wil be seen morefully hereinafter, the length of slots 52 anC 53 will determine thespacing of air gap 22. The shafi 54 then receives thereon a cam 55 whichis rotatable Witt respect to shaft 54 and is secured thereto by means ofz torsion spring 57 which has one end 53 secured to can 55 and the otherend 59 secured to shaft 54.

A spring 55a is connected between arm 15 and pin 54 by means of a pin54b (FIGURE 2) which works througt an opening in shaft 54 to prevent therotation thereof If desired, rotation of shaft 54 could be prevented b5having the ends thereof flattened and fitted with slots 52 and 53. Thespring 55a then biases cam 55 into engage ment with arm 15 asillustrated. Torsion spring 57 i: so loaded that it will bias cam 55 torotate in a counterclockwise direction about shaft 54 as illustrated bythe arrow in FIGURE 3.

The stop mechanism including adjusting screw 36 an: stop 37 is thenreplaced in FIGURE 2 in accordance witt the invention by a shaft 60which is secured in the enclosing side walls of housing 14) and whichcarries a can 61 in a manner similar to that shown in FIGURE 3 for cam55 and shaft 54. That is to say, the shaft 60 and 6 .61 areindependently rotatable with respect to one ther and are secured to oneanother by means of a ion spring 62 schematically illustrated in FIGURE2. only difference between the arrangement of cams 55 61 is that theshaft '64 mounting cam 61 is not secured slotted structure in the sidewalls. A tension spring s then secured between tongue 64 connected tomag- 18 and tongue 65 connected to housing ll. 1 operation and when themagnet 18 is de-encrgized, [1g 31 forces arm 15 counterclockwise aboutpivot 16 ring brake lining 14 into engagement with drum 11. ;he sametime, pin 54 is moved to the left hand side lots 52 and 53 and cam 55 isin contact with operating '15. If, during the operation of the brake,some r occurs in the lining, the brake shoe 13, operating 15 andarmature 21 will have'rnoved to a further Jterclockwise rest position,about pivot 16. Therecam 55 will lose contact with arm 15 after pin 54:hes the end of slots 52 and 53. Since cam 55 is led by torsion spring57, cam 55 will rotate until it n establishes contact with operating arm15. As- ,e now that the solenoid magnet 1% is energized in :r to releasethe brake so that armature 21 and brake 13 and operating arm 15 rotateclockwise about 16. Under this condition the cam 55 and its shaft moveto the right until pin 54 strikes the right hand of slots 52 and 53.Thus the operating arm motion topped but the armature 21 does not yetrest against face of solenoid magnet 18. Note that the gap whichexists'between the armature 21 and magnet 13 is :tly equal to the wearthat occurs on lining t4 durthe preceding application of the brake.Since the met 18 cannot pull armature 21 any closer, the magbody 13 willmove toward the stationary armature 21. log 63 is then extended and thesurface of magnet 13 es cam 61. Accordingly the torsion spring 62 on ft60 will cause cam 61 to rotate in a counterclockwise ction until itagain meets the surface of magnet body Thus the self-adjusting cycle iscompleted so that in the magnet 18 is tie-energized and the brake liningseats on drum 11, the gap 22 will be a gap having a a'nce equal tothedistance through which shaft 54 res in slots 52 and 53.

Vith the present invention it will be observed that miadjustments willoccur during each application and ase of the brake when wear occurs.Therefore, a letermined and reliable small air gap will alwaysmaintained between the armature 21 and magnet 18. :e there will be areliably small constant air gap, the re may nowb'e designed withrelatively smaller and 'efore more economical magnets than thosepresently )loyed in brakes of similar capacities where the magmustgenerate sufiicient ampere turns to overcome tively large air gaps thatmay be encountered before brake is adjusted.

ilthough this invention has been described with re- :t to its preferredembodimentamany variations and lifications will now be obvious to thoseskilled in the and it is preferred therefore that the scope of this:ntion be limited not by the specific disclosure herein only by theappended claims.

; is claimed:

. In a spring set brake comprising a brake drum, a re shoe, an operatingarm, a solenoid and an armaand a spring braking means; said operatingarm lg pivotally mounted at one end thereof, said solenoid lg pivotallymounted at one end thereof; said brake shoe and said armature beingconnected to said 0 crating arm; said brake shoe being positionedadjacent said brake drum and being movable between engagement anddisengagement with respect thereto responsive to movement of saidoperating arm; said armature being mounted adjacent said solenoid andbeing movable from a predetermined air gap spacing when said brake shoeengages said brake drum to engagement therewith responsive toenergization of said solenoid; said spring means being operativelyconnected to said control arm to bias said control arm to apredetermined position; an automatic air gap adjusting structure; saidautomatic air gap adjusting structure comprising first and second stopmeans operatively connected to said operating arm and said solenoidrespectively; said first stop means having stop position control meansconnected thereto for readjusting the stop position of said first stopmeans when said air gap between said armature and said solenoid exceedssome predetermined value.

2. The device or" claim 1 wherein said stop position control meansincludes rotatably biased cam means engaging said control arm and amovable support member for carrying said cam; said movable supportmember being movable over a predetermined distance; said cam normallyengaging said control arm until said movable support member reaches oneof its limits of movement whereby said cam rotates to reestablishcontact with said control arm.

3. The device of claim 1 wherein each of said stop means includes firstand second rotatably biased cam means normally engaging said control armand said solenoid respectively and a movable support member for carryingsaid first cam means; said first cam means normally engaging saidcontrol arm until said movabie support member reaches one or" its limitsof movement whereby said first cam means rotates to reestablish contactwith said control arm.

4. An automatic control means for maintaining a predetermined maximumspacing between a solenoid and an armature; said solenoid and saidarmature being relatively movable away from and toward one another; saidautomatic control means including an adjustable stop member positionedadjacent the side of said armature adjacent said solenoid; saidadjustable stop member including a rotatably biased cam and a movablesupport means for said cam; a fixed support for said movable supportmeans; said fixed support having a slot therein receiving said movablesupport means; said movable support means being movable through apredetermined limited distance defined by the length of said slot; abiasing means connecting said cam and holding said cam in contact withsaid armature until said movable support means reaches the limit of itsmotion defined by said slot whereby said cam rotates to a new positionto be retained in engagement with said armature.

5. The automatic control means substantially as set forth in claim 4which includes a second adjustable stop member connected to saidsolenoid for limiting the position thereof; said second stop membercomprising a second rotatably biased cam;

References Cited in the file of this patent UNITED STATES PATENTS2,830,682 Noon Apr. 15, 1958 3,032,146 Szabo et a1. May 1, 19623,051,275 Knocke Aug. 28, 1962

1. IN A SPRING SET BRAKE COMPRISING A BRAKE DRUM, A BRAKE SHOE, ANOPERATING ARM, A SOLENOID AND AN ARMATURE, AND A SPRING BRAKING MEANS;SAID OPERATING ARM BEING PIVOTALLY MOUNTED AT ONE END THEREOF, SAIDSOLENOID BEING PIVOTALLY MOUNTED AT ONE END THEREOF; SAID BRAKE SHOE ANDSAID ARMATURE BEING CONNECTED TO SAID OPERATING ARM; SAID BRAKE SHOEBEING POSITIONED ADJACENT SAID BRAKE DRUM AND BEING MOVABLE BETWEENENGAGEMENT AND DISENGAGEMENT WITH RESPECT THERETO RESPONSIVE TO MOVEMENTOF SAID OPERATING ARM; SAID ARMATURE BEING MOUNTED ADJACENT SAIDSOLENOID AND BEING MOVABLE FROM A PREDETERMINED AIR GAP SPACING WHENSAID BRAKE SHOE ENGAGES SAID BRAKE DRUM TO ENGAGEMENT THEREWITHRESPONSIVE TO ENERGIZATION OF SAID SOLENOID; SAID SPRING MEANS BEINGOPERATIVELY CONNECTED TO SAID CONTROL ARM TO BIAS SAID CONTROL ARM TO APREDETERMINED POSITION; AN AUTOMATIC AIR GAP ADJUSTING STRUCTURE; SAIDAUTOMATIC AIR GAP ADJUSTING STRUCTURE COMPRISING FIRST AND SECOND STOPMEANS OPERATIVELY CONNECTED TO SAID OPERATING ARM AND SAID SOLENOIDRESPECTIVELY; SAID FIRST STOP MEANS HAVING STOP POSITION CONTROL MEANSCONNECTED THERETO FOR READJUSTING THE STOP POSITION OF SAID FIRST STOPMEANS WHEN SAID AIR GAP BETWEEN SAID ARMATURE AND SAID SOLENOID EXCEEDSSOME PREDETERMINED VALUE.